In dual-energy imaging, two images of the same object are acquired under different x-ray beam conditions, such as beam energy and filtration. For example, high- and low-energy images of the same object can be acquired. The images can then be decomposed to produce material specific images such as soft-tissue and bone-only images.
One method of acquiring dual-energy images involves double-shot acquisition, in which both the high- and low-energy images are acquired using a single pixilated digital detector. Double-shot acquisition promotes detective quantum efficiency and provides an improved detectability index for dual-energy imaging as compared to sandwiched detectors. Double-shot image acquisition, however, introduces the potential for a decrease in final image quality due to patient motion (e.g. cardiac and respiratory motion) that occurs between the two x-ray exposures. This motion can result in severe artifacts in the final decomposed soft-tissue and bone-only images. Artifacts in the decomposed images decrease the clinical efficacy of the data. As such, it is advantageous to acquire the dual-energy images as close in time as possible.
Standard methods of detector acquisition for dual-energy images involve initiating a first image acquisition, reading out the first image information stored in the detector, and then initiating a second image acquisition. The delay between the acquisition of the first and second image due to the time necessary to read out the first image information prior to initiating the second image acquisition may result in artifacts due to patient motion. Although high-speed detectors are available that minimize the necessary read out time, such detectors are expensive and may be cost prohibitive for certain applications. As such, there is a need to provide a method of acquiring high-speed dual-energy images using a pixilated digital detector which eliminates the delay between image acquisitions as a result of data read out.